This Bioengineering Research Partnership (BRP) is focused on technical development and practical application of micro-electric impedance (muEI) technologies to measure/image the time-dependent spatial distribution of passive and excitable membrane properties of auditory and vestibular sensory hair cells. Specific technologies under development include micro-electric impedance spectroscopy (mEIS), microelectric impedance tomography (muEIT) and micro-domain voltage clamp (muVC). These new technologies are being specifically applied to test the piezoelectric wave hypothesis and the ultrasonic resonance hypothesis in cochlear outer hair cells, including how the resonance frequencies of isolated cells are altered by drugs and how the frequencies map onto the cochlea. Electrically evoked mechanical movement of the cells will be correlated with resonance properties. muEl signatures of both auditory and vestibular hair cells are being studied in response to adequate stimuli in control conditions and following application of putative efferent transmitters. The technology to be developed and applied has the potential to record electrical events at microsecond time scales - resolution well beyond existing approaches. Results are contributing to our fundamental understanding of the spatial distribution and temporal response properties of auditory outer hair cells and vestibular utricular hair cells. Perhaps more importantly, muEIT devices to be developed as part of the research, will provide an entirely new window through which to view the living machinery of a wide variety of normal and pathological cells. The project integrates bioelectricity, imaging, bioinstrumentation, micro/nano-bioesensors, physiological modeling/computation, biomechanics and microfluidics. Devices involve on-chip transport of solutions/pharmaceutics and living cells. Conclusive results testing the piezoelectric wave hypothesis and piezoelectric resonance hypothesis are expected within 18 months of the renewal. The work is expected to culminate in continuation year 5 with the development of a practical muEIT system and its application to study the saptio-temporal distribution of excitable properties in hair cells. Dr. Rabbitt, Professor of Bioengineering at the University of Utah, will direct the BRP team.